1. Field of the Invention
The present invention relates, in general, to bill handling, and in particular to the improvement of currency stacker for preventing unauthorized extraction of currency from the stacker which may contain a plurality of currency.
2. Description of the Prior Art
Current bill handling apparatuses include money exchanging or vending machines each provided with a bill validator for identifying the authenticity or denomination of a bill or paper currency inserted therein. When inserted into an inlet of the validator, the bill is conveyed by a belt-pulley arrangement through a sensor which detects optical or magnetic characteristics of the bill. After the bill validator identifies the insertion with a genuine bill from outputs of the sensor, it is then transported to a stacker wherein bills are accumulated for storage while exchanged bills, coins or goods are put out in a tray of the machine. Adversely, if the bill validator can not decide the insertion as a genuine bill, the belt-pulley arrangement is driven in the reverse direction to return the insertion to the inlet. For instance, U.S. Pat. No. 4,628,194 to Bob M. Dobbins, et al. indicates a prior art validator and U.S. Pat. No. 4,722,519 to John Zouzoulas shows a stacker apparatus.
In some cases, a string-like material such as a thread or tape is intentionally attached to one end of a bill which is then inserted into the inlet of the validator. The bill is transported along a passageway in the bill validator by the belt-pulley arrangement through the sensor to the stacker or an escrow compartment as shown in U.S. Pat. No. 4,050,562 to G. A. Schwippert, and an exchange is thrown out on the tray of the apparatus. After that, the bill is pulled back from the apparatus by pulling the string. Many attempts have been made in the past for preventing unauthorized removal of a bill contained within the stacker. However, there have not been proposed any good structure of currency stackers to fully prevent such unauthorized removal of the bill. Also, in case that a stacker together with accumulated bills therein must be transported to a predetermined position, it is very easy for a person to extract bills from prior art stackers since they do not have the structure resistible to unauthorized access thereto.